Device for storing a length of weft thread and introducing it into a shed



Feb. 6, 1968 T. FRANSEN 3,367,372

DEVICE FOR STORING A LENGTH OF WEIFT THREAD AND INTRODUCING I'I INTO A SHED Filed Feb. 16, 1966 2 Sheets-Sheet 1 Feb. 6, 1968 T. FRANSEN DEVICE FOR STORING A LENGTH OF W-EFT THREAD AND INTRODUCING IT INTO A SHED Filed Feb, 16, 1966 2 Sheets-Sheet 2 United States Patent 3,367,372 DEVICE FOR STORING A LENGTH OF WEFT gIIIIlgAD AND INTRODUCING IT INTO A Theodorus Fransen, Deurne, North-Brabant, Netherlands, assignor to N.V. Machinefahriek L. te Strake, Deurne, North-Brabant, Netherlands, a Dutch company liiled Feb. 16, 1966, Ser. No. 527,700 Claims priority, application Netherlands, Feb. 19, 1965, 65-2,157 3 Claims. (Cl. 139127) ABSTRACT 6F THE DISCLOSURE A device for storing a length of weft thread and introducing it into a shed, comprising a shaft adapted to take up by suction a measured length of weft thread in the form of a loop, a channel forming an extension of the shaft, an opening between the shaft and the channel through which a loop of weft thread may be drawn into the shaft, a blowing nozzle associated with the outer end of the channel arranged to blow air outward adjacent such end of the channel, thereby drawing secondary air into such opening and into the channel, to draw a free end of the loop of weft thread into the opening and through the channel and blow it into the shed, a stamp arranged to engage the loop of weft thread at a point adjacent to a portion of the weft thread which has been blown into the shed, a mechanism for holding the stamp in clamping engagement with the thread while the free end of the loop is being drawn through the channel and blown into the shed and then releasing the stamp from the thread to permit the last portion of the loop to be drawn through the channel.

Background of the invention The invention relates to a blowing device for blowing a weft thread into the shed of a loom by means of air under pressure, which blowing device possesses a nozzle for the air under pressure and a channel for presenting a i measured length of a thread to the nozzle, which thread is drawn from a thread package.

When each measured length of the weft thread is to be woven into the fabric in a hairpin like manner in order to obtain a selvage, each thread having a measured length is to be blown into the shed in two steps. Firstly the first leg of the hairpin like weft is blown into the shed, and after the shed is changed, when the second leg of the hairpin like weft is ready to be blown into the shed, the portion of the thread leading back from the first leg runs through the blowing device and the associated channel for presenting the thread to the blowing device. When now the second part of the weft is blown into the shed it can happen that the part of the thread which runs already through the blowing device and the channel is entrained by the strong airstream within the channel, and adheres to the part of the weft which is being blown into the shed, as a result of which the thread becomes entangled and can not be stretched into the shed.

The object of the invention is to remove this drawback so that the dimensions of the channel can be made as small as possible, without the possibility that the thread may become entangled as a result of touching of both thread parts in the channel.

Summary of the invention According to the invention this is attained in that in the interior of the channel a stamp is movable across the conveying direction of the channel into an end position "ice in which a thread is clamped in front of the stamp in this through path.

The stamp is situated at a place where a part of the thread runs, which leads back from the leg that is already blown into the shed. When this part of the thread is clamped by the stamp the part of the thread which runs from the clamp to the fabric is tensioned owing to which this part cannot become entangled with the part of the weft which is to be blown into the shed. At the moment that the thread is to be entirely removed out of the blowing device the clamping action of the stamp is released.

The invention allows the use of very narrow channels, which can have a cylindrical cross section with a relatively small diameter near the blowing nozzle without the possibility that a thread may become entangled. A very strong air stream can be created in this channel by the provision of the narrow cross section of the channel near the blowing nozzle. The invention is very appropriate for a loom in which a channel for presenting a thread possesses a suction opening which can be closed by a valve at its end remote from the blowing nozzle and the passage of the channel is adapted as a flat slot having a dumbbell cross section. The fiat slot can merge into a channel having a round cross section. In this embodiment the stamp is situated near one of the edges of the flat slot at that place where the slot has a larger cross section than the central part of the slot between these edges.

When the channel is provided with a suction opening for the thread at its side the stamp is situated at that side of the internal space of the channel remote from the suction opening.

The invention will now be described by means of an embodiment with reference to the drawings.

Brief description of the drawings FIG. 1 is a longitudinal horizontal section of a blowing device according to the invention;

FIG. 2 is a fragmentary vertical section through a channel showing a stamp in position for releasing a thread extending through the channel;

FIG. 3 is a section similar to that of FIG. 2 showing the stamp in position for clamping a thread;

FIGS. 4-7 are diagrammatic representations of a blowing device according to FIG. 1 in plan view, in which the successive steps of presenting of a weft are incidated;

FIG. 8 is a perspective View of a loom provided with a device embodying the invention.

Description of the preferred embodiment In an apparatus according to the invention the blowing device consists of an annular nozzle 1 of a conventional type, which is positioned around a central supply channel 2 for a thread and for conducting secondary air. A mixing tube 3 is situated in a known manner in front of the nozzle 1, which mixing tube preferably is provided with a slot 4 to accommodate the A-section of a weft thread. By an A-section of a weft thread is meant the first leg of a measured length of weft thread, which is blown into the shed. The B-section of the weft'thread is the second leg of the thread, which is to be blown into the shed later, resulting in a hairpin like formation of the weft woven in the fabric.

The central channel 2 merges into a widened part 2a and further it merges into a channel 2b of a flat shaft 212 of which the internal space is adapted to take up a loop of a thread. The interior of the flat shaft 212 has a symmetrical dumbbell shaped cross section and is a narrow slot having widened edges. A part of this slot is shown in FIGS. 2 and 3, in which the narrow central part is indicated by 2b and the widened edge with 2b". The shaft 2b is adapted for sucking up a measured length of a thread in the shape of a loop, which thread is drawn from a thread package 14 (FIG. 8).

FIG. 8 shows the shaft 2b in its entirety. The lower portion of the shaft 2b is arranged in a verticalposition to conserve space, and is secured to the side plate 16 of the frame of a conventional type of loom shown in FIG. 8. The upper portion of the shaft 2b, which is shown in FIG. 1, extends horizontally. Inside of the shaft 2b is a narrow slot or channel which has a dumbbell-shaped cross section, and this channel possesses a suction opening at its end remote from the blowing nozzle, which opening is controlled by a valve, as hereinbefore described under Summary of the Invention.

As shown in FIG. 8, the thread which is continuously drawn from the thread package 14 passes above the first roller 15 and under the second roller 15 and then passes into an auxiliary shaft 17, the operation of which is similar to the operation of the shaft 2b. FIG. 8 shows that the thread passes from the auxiliary shaft 17 into the shaft 2b and then to the blowing nozzle and the mixing tube 3. These elements through which the thread passes are conventional in a pneumatic loom, and the operation of these elements, which is described in detail in U.S. Patents Numbers 3,024,814 and 3,137,322, may be summarized as follows:

1) At the stage illustrated in FIG. 4, the A-section of the weft thread has been woven into the fabric, and the -B-section of the weft thread extends from the fabric through the blowing nozzle into the shaft 2b, where the thread is stored in the form of a loop. At this stage, the trailing end of the B-section of the weft, which extends out through the opening 5, must be severed from the thread supply. This severing operation is performed by a conventional cutting device, as illustrated in FIG. 3 of U.S. Patent Number 3,137,322, which shows that at the end of the severing operation the trailing end of the B- section of the thread is left free, while the cut end of the.

thread supply remains clamped in the cutting device.

(2) The next operation of a conventional pneumatic loom consists in blowing the B-section of the thread into the shed. This blowing operation is illustrated in FIGS. 4, 5, 6 and 7. During this blowing operation the valve through which a vacuum is applied to the remote end of the shaft 2b is closed, and air under pressure is supplied to the annular blowing nozzle 1, for example through a tube 18. In the conventional pneumatic loom illustrated in FIG. 8, the valves for supplying compressed air and for applying a vacuum to the tubes which lead to various parts of the apparatus are located in a valve housing 19, and each valve is opened and closed at the proper stages by a cam which operates the valve actuator and which is located on a camshaft 20. In the operation of blowing the B-section of the thread into the shed, it is necessary that the free end of the'B-sec-tion be picked up by the air stream so that the free end of the B-section enters the shed first and the remainder of the B-section is pulled after the free end until the B-section is stretched into the shed. The entire section of weft thread, consisting of the A-section and the B-section, will then lie in the proper hairpin formation in the fabric. In the earlier type of pneumatic loom illustrated in U.S. Patent Number 3,137,- 322, the shaft is mounted to oscillate between a loading position and a blowing position, and is provided with two separate blowing nozzles. In the more modern type of pneumatic loom illustrated in the present drawings, the shaft 212 is stationary and is provided with only one blowing nozzle, and the free end of the thread is carried by suction from the opening to the blowing nozzle.

(3) After the B-section of the thread has been blown into the shed, the supply of compressed air to the blowing nozzle is shut off by the valve in the valve housing 19, and vacuum is applied to the shaft 2b. A new loop of thread, which is to form the A-section of the next weft thread, is then drawn into the shaft 2b through the opening 5 in the manner illustrated in FIG. 3 of US. Patent Number 3,024,814. A conventional thread clamp, as described in U.S. Patent Number, 3,137,322, must be provided for engaging the thread at a point where the thread passes from the shaft 17 into the shaft 2b. As explained in that patent, the operation of the clamp must be timed in accordance with the speed with which the thread is supplied by the rollers 15 so that the thread is of the proper length between the clamp and the severed end of the thread supply. After this clamp closes, the suction 1s cut off from the shaft 2b and compressed air is supplied to the blowing nozzle. At the same time, the severed end of the thread supply, which has been clamped in the cutting device as illustrated in FIG. 3 of U.S. Patent Number 3,137,322, is released so that it is drawn into the opening 5 and is carried into the stream of air leaving the blowing nozzle. This stage corresponds to that illustrated in FIG. 1 of U.S. Patent Number 3,137,322. The severed end of the thread supply is thus extended into the shed, pulling after it the loop of thread which has been stored in the shaft 2b. In this way, the A-section of the thread is extended into the shed by the air stream until its movement is arrested by the clamp located between the shaft 17 and the shaft 2b. As indicated hereinbefore, this clamp has been closed at the proper moment to gage the length of the A-section of thread so that the A-section, at the end of the blowing operation, will reach to the remote edge of the fabric but not beyond. While the clamp is closed, the feed rollers 15 continue to turn, but the accumulating slack in the thread is taken up by the shaft 17.

(4) After the A-section of the thread has been blown into the shed, the supply of compressed air to the blowing nozzle is shut off, the thread clamp which is located between the shafts 17 and 2b is opened, and vacuum is applied to the shaft 2b to draw in a new loop of thread, at the same time drawing out the loop which has been stored in the shaft 1 7. This stage is illustrated in FIG. 8, and is also illustrated in FIG. 2 of U.S. Patent Number 3,137,322. As soon as a sufiicient length of thread has been drawn from the thread supply into the shaft 2b to complete the B-section of the weft thread, the cutting device operates, in proper timed relation with the rate at which the thread is supplied by the rollers 15, to sever the B- section of the weft thread from the thread supply. A new cycle then proceeds as hereinbefore described.

The present invention comes into operation only during the stage illustrated in FIGS. 4, 5, 6 and 7, which stage is the blowing of the B-section of the weft thread into the shed. During the preceding blowing stage, the A-section of the weft thread is blown into the shed and the adjoining portion of the thread, which extends back through the blowing nozzle and out of the opening 5 to the clamp that is located between the shafts 2b and 17 is placed under tension as hereinbefore described. Then after the A-section of the thread has been blown into the shed, the supply of compressed air to the blowing nozzle is cut off, the clamp is released, and suction applied to the shaft 2b pulls more thread through the opening 5 to form a loop of thread in the shaft 2b as shown in FIGS. 1 and 4.

A stamp 6 is situated in the shaft 2b. The stamp 6 possesses a stem 7 provided with a head 8 bearing on a lever 9, which has its central portion pivoted beneath a frame member 21 and has its two arms offset vertically as shown in FIG. 8. One of the arms of the lever 9 bears against the head 8 of the stamp 6, and the other arm bears upon a cam 22 on the camshaft 20, which is driven by a rotating part of the loom. The lever 9 in FIG. 2 is situated in such a position that the arm adjacent to the stamp 6 is elevated and the other arm bears upon a low spot on the cam 22, so that the through path of the channel 2b" is entirely free; that is a shoulder 10 of the stamp 6 is situated out of the path through the channel 212. The shoulder 10 is oval in horizontal section, as shown in FIG. 1, and fits in a recess 11 which is provided in the upper side of the shaft 2b and which is oval in horizontal section to receive the oval shoulder of the stamp. A compression spring 12 is situated behind the head 8. The spring 12 presses down the head 8 when the lever 9 moves downwardly, owing to which the shoulder 10 of the stamp 6 will rest on the bottom of the channel 2b". If now a thread is present in the part 2b" of the channel this thread is clamped under the shoulder 10 on the bottom of the channel. Further the stamp 6 is provided with a knob 13 for manually elevating the stamp e.g. when the loom is not operative and a thread which remains under the shoulder 10 of the stamp is to be removed by hand.

The manner in which the stamp frees and clamps the thread will now be described with reference to FIGS. 4-7.

For clea-rness sake the .fabric is diagrammatically drawn at the left side of FIG. 4. The A-thread and the B- thread of the hairpin shaped wefts, which are woven into the fabric are also indicated. When an A-thread is blown into the shed and is beaten into the fell by the reed an adjoining part of the thread runs to the blowing device, because a B-section of the thread is still to be blown into the shed. That part of the thread which remains in the mixing tube will be a part of the B-section after its insertion. The B-section is sucked into the shaft 2b in the shape of a loop through the opening 5 when vacuum is applied at the remote end of the shaft 2b, because the vacuum causes air to flow rapidly inward through the opening 5 and through the channel 2. At this stage the thread runs directly from the notch 4 to the opening 5 and is not clamped outside of the opening 5. Thus the air flowing inward through the channel 2 and the opening 5 pulls upon the thread so as to pull more thread through the opening 5 and to form a loop in the manner illustrated in FIG. 3 of US. Patent Number 3,024,814. The stamp 6 is now in a position as shown in FIG. 2 in which the path through the channel 2b" is entirely free. This position is indicated by a circle in FIG. 4. At the moment that the blowing device becomes operative when air under pressure is blown out of the nozzle 1 the part of the thread which remains in the suction opening 5 enters the interior of the blowing device as indicated in FIG. 5. The manner in which the free end of the thread enters the blowing device is as follows:

This free end is the free end of the B-section of the weft thread. In every pneumatic loom, before the B- section of the weft thread can be blown into the shed, the mechanism must sever the B-section of the weft thread from the thread supply, as indicated in FIG. 3 of US. Patent Number 3,137,322. This severing operation occurs at the stage illustrated in FIG. 4, and the end of the B- section of the thread which extends out of the opening 5 is free after the severing operation. Then when air under pressure is blown out of the nozzle .1, the valve for applying suction to the shaft 2b is closed, so that the shaft 2b constitutes a dead air space and the opening 5 is the only source through which secondary air can enter the channel 2. Under these conditions, the blowing of air under pressure from the nozzle 1 creates a jet action which draws secondary air through the channel 2 and creates a powerful suction at the opening 5, which draws the free end of the B-section into the opening 5 and through the secondary air channels 2a and 2 into the jet of air streaming from the nozzle 1. Before this blowing operation begins, the B-section of the thread has been formed into a loop in the shaft 2b, as indicated in FIGS. 1 and 4, in the manner hereinbefore explained. When the free end of the B-section of the thread is sucked into the opening 5 and then into the channels 2a and 2, it begins to pull thread from one side of this loop.

Except for the action of the free end of the thread in pulling thread from one side of the loop, the loop of thread in the shaft 2b, as indicated in FIG. 5, remains undisturbed because the interior of the shaft 2b is a dead air space, as hereinbefore described.

However, if the clamp 6 were to remain open as shown in FIG. 2, or if no such clamp were provided, the air stream issuing from the nozzle 1 not only would entrain the free end of the B-section of thread, but also would tend to entrain the portion of the B-section which extends through the nozzle and is connected to the A-section. Such undesired entrainment would cause the blowing device to draw out both legs of the loop of thread from the shaft 2b, instead of producing the desired effect of drawing out only the leg connected to the .free end of the B-section of thread. Such undesired entrainment of both legs of the loop of thread in the shaft 2b, which would occur in the absence of the clamp 6, is indicated in dotted lines in FIG. 5.

FIG. 6 shows the desired proper action of the thread in solid lines, and shows in dotted lines the undesired entr-ainment of the portion of the thread which should remain undisturbed.

FIG. 7 shows also in solid lines the desired action of the thread, and shows in dotted lines the undesired tangled condition of the B-section of thread which would prevent the B-section of thread from extending straight into the fabric and from reaching entirely across the fabric as desired.

In accordance with the invention, the clamp 6 operates to prevent the undesired action of the thread which is shown in dotted lines in FIGS. 5, 6 and 7, and to produce the desired action of the thread which is shown in solid lines, in the following manner: At the moment or shortly before the moment when air under pressure streams out of the blowing device, the cam 22 actuates the lever 9 so that the stamp 6 moves downwardly and the part of the B-section which leads to the A-section of the thread is clamped. This situation is indicated by a solid dot at the stamp 6 in FIG. 5.

The leading end of the B-thread which is sucked into the interior of the blowing device through the opening 5 is urged in the direction of the shed so that the loop shaped part of the thread in the shaft 2b is drawn away and the thread travels in the-manner shown in solid lines in FIGS. 5, 6 and 7. The part of the B-section which is connected to the A-seotion of the thread is prevented from being entrained in the air stream, by the action of the stamp.

The B-t-hread is entirely blown into the shed and the situation shortly before the B- thread leaves the shaft 2b is indicated in FIG. 6. The stamp 6 is about to free the thread. The cam 22 then actuates the lever 9 to move the stamp 6 to the position shown in FIG. 2. The stamp 6 has entirely freed the channel 2b in FIG. 7 and the last part of the loop of the B-thread leaves the mixing tube 3.

I claim:

1. A device for storing a length of weft thread and introducing it into a shed, comprising a shaft adapted to take up by suction a measured length of weft thread in the form of a loop, a channel forming an extension of the shaft, an opening between the shaft and the channel through which a loop of weft thread may be drawn into the shaft, and a blowing nozzle associated with the outer end of the channel and arranged to blow air outward adjacent such end of the channel, thereby drawing secondary air into such opening and into the channel, to draw a free end of the loop of weft thread into the opening and through the channel and blow it into the shed, wherein the improvement comprises a stamp arranged to to engage the loop of weft thread at a point adjacent to a portion of the weft thread which has been blown into the shed, and mechanism for holding the stamp in clamping engagement with the thread while the free end of the loop is being drawn through the channel and blown into the shed and then releasing the stamp from the thread to permit the last portion of the loop to be drawn through the channel.

2. A device according to claim 1 wherein the interior of the shaft is a flat slot having a dumbbell-shaped cross section which is wider adjacent the edges of the slot, and

vthe stamp is arranged to enter one of the wider edge the wider edge portions of the slot and the stamp is arportions of the slot to clamp a thread that extends through 'ranged to enter the other edge P {ion of the s-uch edge portion.

3. A device according to claim 2 wherein the opening No references clted' between the shaft and the channel is adjacent to one of 5 HENRY S JAUDON, P i E min r, 

